1. Field of the Invention
The invention relates to a power storage device having positive electrodes and negative electrodes stacked on top of each other with electrolytes interposed in-between and to a method for manufacturing such a power storage device.
2. Description of the Related Art
In recent years, as the large-capacity batteries used for electric vehicles and so on, various secondary batteries having a high energy density and a high output power density have been developed. As one of such secondary batteries, a bipolar type battery that uses bipolar electrodes as it electrodes is known.
A bipolar type battery is constituted of bipolar electrodes stacked on top of each other with electrolytes interposed in-between. Each bipolar electrode has a current collector, a positive electrode formed on one side of the current collector, and a negative electrode formed on the other side of the current collector. In order to prevent positional errors of the components of the stack of such a bipolar type battery, a method is used in which position markings are made at the components of the stack, such as electrodes, and the components are then stacked up by referring to the position markings.
Japanese Patent Application JP-A-2001-102050 describes an electrode structure of a stack-based battery/capacitor, in which positive electrode plates and negative electrode plates are stacked with insulative separators interposed in-between, as shown in FIG. 4. More specifically, referring to FIG. 4, a stack-based battery/capacitor described in this publication has separators 122a, 122b, and positioning portions 124a and 124b, or positioning portions 126a and 126b, are formed at the separators 122a, 122b. The positioning portions 124a, 124b, 126a, and 126b are in contact with corresponding side portions of positive electrodes 100 and negative electrodes 116.
According to such a method in which components are stacked by referring to markings, however, the components of the stack may be displaced from their positions when external force acts on the components in the direction perpendicular to the axis of the stack, and therefore the dimensional accuracy of the stack may become insufficient. Further, according to the method described in Japanese Patent Application JP-A-2001-102050, the positive electrode plates 100 and the negative electrode plates 110 may bend when they come into contact with the positioning portions 124, 124b, 126a, and 126b due to the external force acting in the direction perpendicular to the axis of the stack. In particular, if this structure is used for a bipolar type battery, because the stack components, such as current collectors, have a relatively small thickness and thus a relatively low strength, problems, such as bending of the components, may easily occur, and therefore the positioning accuracy may deteriorate.
U.S. Pat. No. 5,047,301 discloses a battery capable of extended operation at high temperature which battery includes a cell of laminated construction utilizing a solid oxidant cathode, an electrolyte element, a catalyst and a gas impermeable separator sheet providing an anode for the cell, with each element in electrical connection with the next. The solid oxidant is a mixture including powdered manganese dioxide, carbon and caustic material, the electrolyte element is a mixture including powdered magnesium oxide, and a binder, pressed into a solid pellet and soaked with caustic material. The cell further has a porous carbon paper substrate in electrical contact with the gas impermeable separator sheet and the catalyst is platinum dispersed on and adhered to the substrate. A source of hydrogen gas is provided, and when the battery is exposed to the hydrogen gas, a voltage is generated.